Abstract: A first characteristic of a first discharge of electrodes of a pulse power drilling assembly in a borehole of a subterranean formation is determined. The first characteristic is based on a measurement of the first discharge. A second characteristic of a second discharge of the electrodes is determined. The second discharge occurs after the first discharge, and the second characteristic is based on a measurement of the second discharge. A difference between the first characteristic and the second characteristic is determined. A boundary layer of the subterranean formation is determined based on the difference.

Abstract: A power condition system is disclosed for conditioning power for charging of at least one capacitive element of a pulse power electrode, where the electrical power is received from at least one of a downhole alternator or generator. The received electrical power is rectified and controlled for both voltage and current amplitude. The electrical power is then split into two parallel square wave signals. The electrical power is then transformed, using parallel high frequency high voltage transformers, to a high voltage signal. The high voltage signals are rejoined and rectified to produce a high voltage DC signal. The DC signal is smoothed at a high capacity inductor and output via a switching element to at least one capacitive element of the pulse power electrodes.

Abstract: Methods and system for controlling downhole pulse power operation are disclosed. A method may include detecting a pulse signal discharged between pulse power drilling (PPD) electrodes and determining an arc characteristic of the pulse signal. The method may further include adjusting pulse power applied to the PPD electrodes based, at least in part, on the determined arc characteristic of the pulse signal.

Abstract: A method of communication along a shared voltage line is disclosed. In pulse power drilling, a generator charges applies voltage to a shared voltage line, which capacitively charges electrodes for formation drilling. While the generator controls the charging rate, charge voltage, and post-delay time between the charging cycles, a pulse power controller determines the pre-delay time by firing electrodes to discharge the stored voltage. Communication from the pulse power controller to the generator is encoded in the pre-delay time, where pre-delay times longer than a minimum pre-delay time correspond to time bins with pre-determined communications between the pulse power controller and the generator. The generator can also communicate to the pulse power controller via manipulation of the post-delay time.

Abstract: A downhole tool, in some embodiments, comprises a casing collar locator (CCL) to generate a signal that indicates the presence of a casing discontinuity; and a modulator, coupled to the CCL, to modulate fixed-wavelength light in a fiber optic cable based on said signal.

Abstract: A system, in some embodiments, comprises: a light source; a fiber optic cable coupled to surface equipment and to downhole equipment and illuminated with fixed-wavelength light by said light source; and a modulator to modulate said fixed-wavelength light in the fiber optic cable to communicate data between the surface equipment and the downhole equipment, wherein the modulator uses a modified half-duplex telemetry scheme.

Abstract: A method and system method for determining motion of a downhole tool and feeding back drilling performance. The method may comprise taking a synchronous tool face measurement of the downhole tool, taking a synchronous pulse-echo acquisition to estimate a shape of a borehole, inputting at least the shape of the borehole, the center trajectory of the downhole tool, the rotational time of the downhole tool, the position of the downhole tool, and the one or more measurements of the downhole tool into an information fusion for drilling dynamics, identifying at least one of a whirl, a vibration, or a stick-slip of the downhole tool, and identifying one or more borehole condition and a drilling efficiency. A system may comprise a downhole tool, at least two transducers, and an information handling system.

Abstract: An example method for determining borehole acoustics using an electromagnetic sensing apparatus may include positioning a downhole tool within a borehole disposed in a formation. The downhole tool may comprise at least one acoustic source and at least one electromagnetic (EM) sensor. An acoustic wave may be emitted from the at least one acoustic source. The acoustic wave may generate an electrical signal when an EM field is present within the borehole. The electrical signal may be measured with the at least one EM sensor. At least one downhole characteristic may be determined based, at least in part, on the measured electrical signal.

Abstract: In an example implementation, communications between a downhole logging tool and surface computing subsystem can be provided through a cable that includes one or more electrical conductors. To allow multiple channels of data to be transmitted along a single multi-conductor cable, data can be divided into two or more different channels, and each channel of data can be transmitted along the conductors. Due to the length of the cable, the electrical conductors of the cable may be subject to strong capacitive and inductive coupling. As a consequence of this coupling, signals sent downhole along any two arbitrary conductors may be subject to distortion, and can produce significant “crosstalk” on the other conductors. The effects of crosstalk can be reduced in a variety of ways, for example using QR decomposition.

Abstract: A method and system according to which electrical communication is established between a primary circuit positioned inside a downhole tubular and a secondary circuit positioned outside the downhole tubular. In an exemplary embodiment, the method includes positioning the secondary circuit outside the downhole tubular, the secondary circuit including a magnetically permeable secondary core and a secondary winding extending proximate the secondary core; positioning a primary circuit inside the downhole tubular, the primary circuit including a magnetically permeable primary core and a primary winding extending proximate the primary core; and supplying electrical power and/or data to the primary winding with an electrical source so that a magnetic flux is channeled through the primary and secondary cores to induce an electromotive force in the secondary winding, thus establishing electrical communication between the primary and secondary circuits to transfer power and/or data therebetween.

Abstract: A system, in some embodiments, comprises: a light source; a fiber optic cable coupled to surface equipment and to downhole equipment and illuminated with fixed-wavelength light by said light source; and a modulator to modulate said fixed-wavelength light in the fiber optic cable to communicate data between the surface equipment and the downhole equipment, wherein the modulator uses a modified half-duplex telemetry scheme.

Abstract: A downhole tool, in some embodiments, comprises a casing collar locator (CCL) to generate a signal that indicates the presence of a casing discontinuity; and a modulator, coupled to the CCL, to modulate fixed-wavelength light in a fiber optic cable based on said signal.

Abstract: A method and apparatus according to which electrical communication is established between a primary circuit positioned inside a downhole tubular and a secondary circuit positioned outside the downhole tubular. In an exemplary embodiment, the method includes positioning the secondary circuit outside the downhole tubular, the secondary circuit including a magnetically permeable secondary core and a secondary winding extending proximate the secondary core; positioning a primary circuit inside the downhole tubular, the primary circuit including a magnetically permeable primary core and a primary winding extending proximate the primary core; and supplying electrical power and/or data to the primary winding with an electrical source so that a magnetic flux is channeled through the primary and secondary cores to induce an electromotive force in the secondary winding, thus establishing electrical communication between the primary and secondary circuits to transfer power and/or data therebetween.

Abstract: An example method includes determining a frequency response of a tuned pulse to be transmitted from a transmission element. A matching frequency envelope corresponding to a frequency envelope of the frequency response may be determined. A time domain signal corresponding to the matching frequency envelope may be determined. A series of digital pulses corresponding to the time domain signal may be determined. An analog output at a switching amplifier corresponding to the series of digital pulses may be generated. A transmission element may be excited with the analog output.

Abstract: An example method includes determining a frequency response of a tuned pulse to be transmitted from a transmission element. A matching frequency envelope corresponding to a frequency envelope of the frequency response may be determined. A time domain signal corresponding to the matching frequency envelope may be determined. A series of digital pulses corresponding to the time domain signal may be determined. An analog output at a switching amplifier corresponding to the series of digital pulses may be generated. A transmission element may be excited with the analog output.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to transmit energy as transmitted signals from current electrodes on a galvanic down hole tool, while multiplexing the energy in both time and frequency domains, to interact the transmitted signals with a geological formation to provide interacted signals that represent a formation property. Additional apparatus, systems, and methods are described.

Abstract: In an example implementation, communications between a downhole logging tool and surface computing subsystem can be provided through a cable that includes one or more electrical conductors. To allow multiple channels of data to be transmitted along a single multi-conductor cable, data can be divided into two or more different channels, and each channel of data can be transmitted along the conductors. Due to the length of the cable, the electrical conductors of the cable may be subject to strong capacitive and inductive coupling. As a consequence of this coupling, signals sent downhole along any two arbitrary conductors may be subject to distortion, and can produce significant “crosstalk” on the other conductors. The effects of crosstalk can be reduced in a variety of ways, for example using QR decomposition.

Abstract: Apparatus, systems, and methods may operate to determine the rotating magnetic tool face associated with a rotating section of a drillstring, to determine angular displacement between the rotating section of the drillstring and a substantially fixed section housing the rotating the section, and to determine the magnetic tool face of the substantially fixed section by combining the rotating magnetic tool face and the angular displacement. Additional apparatus, systems, and methods may operate in a similar manner to determine tool face locations.

Abstract: An example method for determining borehole acoustics using an electromagnetic sensing apparatus may include positioning a downhole tool within a borehole disposed in a formation. The downhole tool may comprise at least one acoustic source and at least one electromagnetic (EM) sensor. An acoustic wave may be emitted from the at least one acoustic source. The acoustic wave may generate an electrical signal when an EM field is present within the borehole. The electrical signal may be measured with the at least one EM sensor. At least one downhole characteristic may be determined based, at least in part, on the measured electrical signal.

Abstract: In some embodiments, an apparatus and a system, as well as a method and an article, may operate to transmit energy as transmitted signals from current electrodes on a galvanic down hole tool, while multiplexing the energy in both time and frequency domains, to interact the transmitted signals with a geological formation to provide interacted signals that represent a formation property. Additional apparatus, systems, and methods are described.